Microseparator based-on 4-phase travelling wave dielectrophoresis for lab-on-a-chip applications

摘要

Separation of micron-sized particles is a challenge by highly miniaturized channel systems. In order to offer the ability of smaller volumes and high throughput in Lab-on-a-chip devices more miniaturized components are needed. Due to very low Reynolds number of buffer fluid, microseparators based on travelling wave dielectrophoresis effect have a good efficiency in such applications. In the present paper, a microchannel technique based on surface micromachining is modified to a microseparator. The proposed device is a miniaturized 4-phase travelling wave microseparator with the height of 5 μm, which can be used for separation of biological particles such as cells and some types of viruses. According to numerical simulations, the device can separate and sort different species, as well as different sized cells of the same species. Due to fabrication process, the electrodes made of highly doped poly-silicon are covered by a thin silicon-nitride layer. Additional advantage of the silicon-nitride layer over electrode arrays is the prevention of high electric field gradient. The effect of this thin insulating layer on functionality of the microseparator has been investigated. The simulation results show that a good separation occurs in the frequency range of 1MHz, when electrical conductivity of buffer fluid is near 1ps/m. The fabrication process is presented and influences of other parameters such as permittivity of fluid and fluid conductivity on the operation of the separator are discussed.